I got a check engine light with a 1740 code.
What is it?

 

P-1740 TCC or O/D solenoid performance. Code set when the expected RPM drop is not achieved while attempting to engage TCC and/or O/D.


(Got this from a 1999 service manual.)

 

Possible input shaft seals or torque convertor. Could be a valve hanging up in the valve body, but unlikely. There was a tsb for the 46re trans with this code that required a cover on the valve body to be replaced, but looking up your truck by application nothing shows for the 47re.

....Ok I dropped back a year and there is a tsb (21-08-00) that applies to 2000 california trucks built between March 2, 1999 and Oct 1, 1999 (MDH 0302XX to MDH 1001XX) MDH is on your door sticker. Just a FYI as it probably doesn't apply to your truck.